1. Field of the Invention
The invention relates to hydrocyclones for ballast water treatment. The invention further relates to ballast water treatment systems comprising such hydrocyclones and methods of operating such hydrocyclones and ballast water treatment systems.
Ballast water intake is essential on cargo vessels in order to maintain a high degree of control and stability. During loading of ballast water, large volumes of sediment and marine species from the water columns and harbour floor are sucked into the ballast tanks. Upon deballasting at the vessel's destination, these species can be released into an alien environment. Frequently, the released species are no longer under control of their natural predators and can rapidly multiply in the new environment, thereby forming an invasive threat. Open-ocean exchange of ballast water is practiced with much difficulty, and current methods of ballast sludge removal induce large costs.
Furthermore, sediments sucked into the ballast tanks are difficult to remove therefrom and effectively accumulate in the ballast tanks. The accumulated sediments reduce the capacity of the cargo hold and cause problems with stability.
2. Description of the Related Art
Various methods have been exercised so far to reduce entry of marine species and sediments into ballast water tanks. For example, DE 203 02 516 U1 describes a ballast water treatment system comprising an array of hydrocyclones and optionally a reversible flow filter. The hydrocyclones are intended to remove particles with a density at least slightly higher than that of sea water, thereby producing a particle-reduced overflow stream. The system further comprises, for decontamination of the overflow stream, biocide injection means and/or UV irradiation means. The decontaminated overflow stream is then fed into a vessel's ballast tanks. The dimensions and operation parameters of the ballast water treatment system of DE 203 02 516 U1 are not disclosed therein.
It was an object of the present invention to optimise apparatus, systems and methods of operation for ballast water treatment systems, particularly of the type of system described in DE 203 02 516 U1.